Telephone



Parent @rrrea JOSEPH GHEEVER, OF SOMERVILLE, MASSACHUSETTS.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 291,684, dated January8,. 1884. Application filed February 15, 1883. (No model.)

1'0 all whom, it may concern.

. Be it known that I, J OSEPH H. CHEEVER, of Somerville, in the countyof Middlesex and State of Massachusetts, have invented certain 5Improvements in Telephones, of which the following is a specification. MMy invention relates to magneto-telephones, and has for its object theproduction of an iny strument that will both transmit and receive 1ospeech with great distinctness of articulation,

and great volume.

The principal feature of this invention is the y 1 employment of two'diaphragms, preferably of p iron, these diaphragms forming one a com-:mon north pole-piece and the other a common south pole-piece for anumber of magnets arranged radially around and connected with thediaphragms. Referring to the drawings accompanying this specification,Figure 1 is a rear view of (the diaphragms, showing the magnetsradiating therefrom. Fig. 2 is a sectional view, showing anelectro-magnet attached to the diaphragms. instrument.

A suitable wooden frame, F, has a mouthpiece, M, fitted therein. On therear of the upright portion of the frame F is a recess, g and coveringthis and fastened by its edges is 3 o adiaphragm, D. This diaphragm isfastened to the frame with screws B, which, passing through the northends of magnets N and through the diaphragm, serve to hold the magnetsin contact with the diaphragm, and both to the wooden frame M. Themagnets N S are curved or made U shape, and have their south ends, S,connected radially with a second diaphragm, I. Between these twodiaphragms, and of a thickness nearly equaling thespace between thediaphragms, is a coil, 0, of insulated copper or iron wire. This coil ismade of large diameter relative to its .phragms. The terminals of thiscoil are to be fconnected with the line-circuit, in the usual manner.

In Fig. lfthere are eight permanent magnets, shown as connected radiallyaround and I with the edge of the diaphragms, but the numg her may beincreased to as many as can be se-. H cared to the diaphragms or thereis room for.

Fig. 3 is a section of the entire thickness, and is nearly as wide asthe dia-.

in the vicinity of the coil, which may be in creased to great strengthby the use of large diaphragms and strong electro-magnets.

In speaking-near to the mouthpiece both diaphragms are set in vibration,although the rear one in a lesser degree. Its inductive effects areadded to that of the front diaphragm,

D, because, being of an opposite polarity to the diaphragm D and beingon the opposite of the coil, its inductive effect is similar incharacter to that of the diaphragm D; hence there is no neutralization,and the combined effects of both diaphragms are utilized.

The coil 0 is made of fine wire preferably, as there is a large numberof convolutions of wire exposed to the inductive action of thediaphragms by so making.

This telephone acts equally well as a re ceiver and transmitter, andwhen two are connected together in circuit, speech uttered in one willset its diaphragms in vibration, causing alternating currents ofelectricity of an undulatory character, to be induced in the coilthereof, which currents, passingover the connecting-wires to the secondtclephone,will cause the diaphragms in the latter to vibratesynchronously with'the former, thus repro ducing the speech uttered.

I am aware that telephones have been made with diaphragms charged so asto be of a north polarity on one face and a south p0 larity on theother; also,tl1at a diaphragm has been made having magnets the northends of which are united, so as to form a pole-piece for a coil of wire,and the south ends placed near to or in contact with the diaphragm.

I do not claim, broadly, the charged diaphragm.

I claim- In a telephone, the combination, with two diaphrams one ofwhich constitutes a common north pole-piece and the other a common inthe presence of two subscribing witnesses, south pole-piece of a numberof electro or this 13th day of February, 1883. permanent ma nets of acoil of insulated wire placed betweeil said diaphragms or pole- I JOSEPHOHEEVER' 5 pieces, and to be included in the line-circuit, substantiallyas and for the purpose described. In testimony whereof I have signed myname,

Witnesses:

GEO. XVILLIs PIERCE, D. E. RICHARDS.

